JP3702242B2 - A / E converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an A / E converter that converts back pressure from a probe into an electrical signal.
[0002]
[Prior art]
Conventionally, an air micrometer 801 has been used to measure the inner diameter of a workpiece as shown in FIG.
[0003]
The air micrometer 801 is configured to be supplied with air of stable pressure from an air supply source 811 via a filter 812, a mist separator 813, and a precision regulator 814. The supplied air is configured to be supplied to a measurement nozzle 816 that is a measuring element via a sensitivity adjustment aperture 815 that determines measurement sensitivity, and the air supplied to the measurement nozzle 816 is zero. It is configured to be discharged through a zero adjustment throttle 817 and a silencer 818 for adjustment.
[0004]
The sensitivity adjustment aperture 815 is provided with a pressure sensor 821 in parallel. The pressure sensor 821 receives air pressure from the precision regulator 814 and supplies air to the measurement nozzle 816. A back pressure is input. The pressure sensor 821 is a sensor that converts a change in the back pressure into a resistance value, and is connected to an amplifier 822 that is an A / E converter.
[0005]
The amplifier 822 is configured to output a voltage that changes according to the resistance value, and the amplifier 822 is provided with a changeover switch 831 as shown in FIG. The changeover switch 831 is provided inside the casing 832 of the air micrometer 801 and is configured to be operated by removing the main body cover.
[0006]
The changeover switch 831 includes a plurality of switches 841,..., And the measurement range can be switched between 20 μm, 25 μm, and 50/100 μm depending on the on / off state of each switch 841. Has been.
[0007]
[Problems to be solved by the invention]
However, in recent years, with the demand that the measurement range is set to 10 μm and the reduction in the jet diameter of the measurement nozzle 816, there is an increasing demand for switching to more measurement ranges and amplification sensitivity.
[0008]
In this case, it is necessary to cope with the switch switching 831 described above, or by changing the connection of the jumper pin, changing the wiring of the internal circuit, or exchanging the resistor. In these cases, it is necessary to remove the main body cover or remove the amplifier 822 as the A / E converter, and it is difficult to change the range on the user side.
[0009]
The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide an A / E converter that can easily change a measurement range.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the A / E converter according to claim 1 of the present invention, in the A / E converter for converting the back pressure from the measuring element into an electric signal, the back pressure from the measuring element. Voltage output means for outputting a voltage that changes according to the magnitude of the signal, digital signal input means for inputting a digital signal from the outside, and from the voltage output means with a gain according to the digital signal from the digital signal input means And an external output means for outputting an output signal corresponding to the voltage amplified by the amplification means to the outside.
[0011]
That is, when changing the amplification sensitivity or changing the measurement range in accordance with the reduction of the jet diameter of the probe, a digital signal is input from the outside by the digital signal input means. Then, after the voltage output from the voltage output means that changes according to the magnitude of the back pressure from the probe is amplified by the amplification means with a gain corresponding to the digital signal, the output signal corresponding to this voltage is It is output to the outside via an external output means.
[0012]
For this reason, the voltage that changes according to the back pressure from the probe is amplified with a gain according to the input digital signal and then output to the outside as an output signal according to this voltage, and is amplified according to the digital signal. Changes to sensitivity and measurement range are made.
[0013]
The A / E converter according to claim 2 further comprises a zero adjustment signal output means for outputting a zero adjustment signal having a voltage corresponding to a digital signal inputted from the outside, wherein the external output means is the amplification means. The zero adjustment signal from the zero adjustment signal output means is added to the voltage amplified in step (a) to form the output signal.
[0014]
That is, a zero adjustment signal composed of a voltage corresponding to an externally input digital signal is output from the zero adjustment signal output means, and the external output means adds the zero adjustment signal to the voltage amplified by the amplification means. After forming the output signal, this output signal is output.
[0015]
For this reason, the voltage that is changed according to the back pressure and amplified by the above-described gain is relatively moved by the zero adjustment signal that is changed according to the digital signal, and the air circuit straight line for each measurement range. The optimal condition can be obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
[0017]
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an A / E converter 1 according to the present embodiment. The A / E converter 1 electrically generates back pressure from a probe such as a measurement nozzle that measures the inner diameter of a workpiece. It is a device that converts it into a signal.
[0018]
The A / E converter 1 is connected to a differential pressure sensor 11 with a built-in air micrometer, and the differential pressure sensor 11 is connected to the reference pressure and measuring element supplied to the air micrometer, as in the prior art. The back pressure from is supplied. This differential pressure sensor 11 includes five semiconductor strain gauges 12,..., And these semiconductor strain gauges 12,... Have resistance values according to the magnitude of the back pressure from the probe. It is configured to change. A bridge circuit 13 is formed by these semiconductor strain gauges 12,.
[0019]
The A / E conversion device 1 is formed with a constant current supply unit 21 that supplies a constant current to the bridge circuit 13 of the differential pressure sensor 11, whereby the bridge circuit 13 in the differential pressure sensor 11 is formed. By supplying a constant current of 1.5 mA to the supply terminal, the voltage output from the bridge circuit 13 changes according to the magnitude of the back pressure from the probe.
[0020]
An output from the bridge circuit 13 of the differential pressure sensor 11 is input to the first amplifying unit 42 via a jumper pin 41 for polarity switching. The first amplifying unit 42 is configured by an amplifying IC 43 capable of gain adjustment, and an output from the bridge circuit 13 is input via the jumper pin 41.
[0021]
A second amplifying unit 51 is connected to the output of the first amplifying unit 42. A third amplifying unit 71 is connected to the output of the second amplifying unit 51. The third amplifying unit 71 includes an operational amplifier 72, a digital IC 73, resistors 74 to 76, and a capacitor 78, and the output of the second amplifying unit 51 is input to the digital IC 73. The digital IC 73 is connected to the 10th to 17th pins assigned as the digital input unit 82 to the connector 81 via the 8-bit bus 79, and the A / E converter 1 is connected via the connector 81. For example, a digital signal from the outside of the casing of the air micrometer equipped with can be input from a microcomputer board.
[0022]
One input terminal 91 of the operational amplifier 72 is grounded and connected to the digital IC 73, and the other input terminal 92 is also connected to the digital IC 73. The output terminal 93 of the operational amplifier 72 is connected to the first pin assigned as the analog output unit 94 to the connector 81 via the resistor 76, and the outside of the casing of the air micrometer is connected via the connector 81. It is configured to output analog signals. The output from the output terminal 93 of the operational amplifier 72 is fed back to the digital IC 73 via the resistor 74.
[0023]
The digital IC 73 outputs the output of the second amplifying unit 51 to the other input terminal 92 of the operational amplifier 72 of the third amplifying unit 71 at a division ratio according to the digital signal input from the bus 79. The gain of the third amplifying unit 71 can be changed in 256 steps according to an 8-bit digital signal.
[0024]
And, the 15th pin assigned to the connector 81 as the power input unit 101 is supplied with + 15V power, the 7th pin is supplied with an analog ground line, and the 6th pin is supplied with −15V power. Electrolytic capacitors 102 and 102 are connected between the 5th and 7th pins and between the 7th and 6th pins. Thus, an analog power supply unit 103 used in the A / E converter 1 is formed.
[0025]
In the present embodiment according to the above configuration, when changing the amplification sensitivity and the measurement range in accordance with the reduction in the jet diameter of the probe, the digital input unit 82 assigned to the connector 81 A digital signal is input from the outside of the air micrometer incorporating the A / E converter 1 through a microcomputer board or the like. Then, the digital IC 73 of the third amplifying unit 71 converts the output from the second amplifying unit 51 into the other input of the operational amplifier 72 of the third amplifying unit 71 at a division ratio according to the digital signal input from the bus 79. Output to the terminal 92.
[0026]
For this reason, the gain by the third amplifying unit 71 can be changed in 256 stages according to the input 8-bit digital signal, and this output is sent to the operational amplifier 72 and the connector 81 of the third amplifying unit 71. It is possible to output to the outside of the air micrometer via the assigned analog output unit 94. Thereby, the change to the measurement range according to the digital signal can be realized.
[0027]
Therefore, when changing to a range other than the preset measurement range, or when changing to a larger number of measurement ranges, change the switch provided in the device body, change the jumper pin connection, change the internal circuit wiring, Compared to the conventional case that requires replacement of the resistance, the operation of removing the main body cover or removing the built-in substrate is not required. Thereby, the range can be changed by the user, and convenience is improved.
[0028]
(Second Embodiment)
[0029]
FIG. 2 does not show the second embodiment of the present invention, and the same parts as those in the first embodiment are denoted by the same reference numerals, the drawings are omitted, the description is omitted, and different parts are attached. Only explained.
[0030]
That is, the output from the second amplifying unit 51 is connected to the input terminal 202 of the digital IC 73 in the third amplifying unit 71 via the resistor 201. In addition, an output from the zero adjustment unit 203 is input to the input terminal 202.
[0031]
The zero adjustment unit 203 includes an operational amplifier 211, a digital IC 212, resistors 213 and 214, and capacitors 215 and 216. The 8-bit bus 79 is connected to the digital IC 212 so that a digital signal from the outside of the casing of the air micrometer can be input through the connector 81, for example, from a microcomputer board.
[0032]
One input terminal 221 of the operational amplifier 211 is grounded and connected to the digital IC 212, and the other input terminal 222 is also connected to the digital IC 212. The output terminal 223 of the operational amplifier 211 is connected to the input terminal 202 of the digital IC 73 in the third amplifier 71 together with the output of the second amplifier 51 via the resistor 213.
[0033]
The digital IC 212 is configured so that the zero adjustment signal output to the operational amplifier 211 can be changed in 256 steps in accordance with the 8-bit digital signal input from the bus 79. Thereby, the output from the operational amplifier 211 can be changed, and the voltage of the zero adjustment signal is added to the output voltage from the second amplifying unit 51, and the digital IC 73 in the third amplifying unit 71 is added. It is comprised so that it may be added to the input terminal 202.
[0034]
FIG. 3 shows a block diagram thereof, in which the voltage from the differential pressure sensor 11 is amplified by the amplifier 301 which is the first and second amplifying units 42 and 51, and the output is the third amplifying unit 71. Output to the first D / A converter 302. In the first D / A converter 302, the signal is amplified with a gain corresponding to setting data input as a digital signal from the bus 79, and then output to one terminal 304 of the sum operation circuit 303.
[0035]
On the other hand, the reference voltage obtained from the constant voltage power source is input to the second D / A converter 311 as the zero adjustment unit 203, and is input as a digital signal from the bus 79 in the second D / A converter 311. A voltage corresponding to the setting data is output to the other terminal 312 of the sum operation circuit 303 as a zero adjustment signal.
[0036]
As a result, the output from the differential pressure sensor 11 amplified by the gain in the first D / A converter 302 is output from the output terminal 321 of the sum calculation circuit 303 to the zero from the second D / A conversion amplifier 311. The adjustment signal is combined and output.
[0037]
That is, as shown in FIG. 4A, the first D / A converter 302 functions as a variable resistor 401 that varies and outputs the input from the amplifier 301, and the second D / A conversion amplifier. As shown in FIG. 4B, reference numeral 311 is configured to function as a variable resistor 402 that receives a reference voltage from the constant voltage power source and variably outputs it.
[0038]
In the present embodiment according to the above configuration, when changing the measurement range by switching the amplification sensitivity in accordance with the reduction of the jet diameter of the probe or the like, via the digital input unit 82 assigned to the connector 81, A digital signal is input from the outside of the air micrometer incorporating the A / E converter 1 by a microcomputer board or the like. Then, the digital IC 73 of the third amplifying unit 71 outputs the output from the operational amplifier 52 of the second amplifying unit 51 with the division ratio according to the digital signal input from the bus 79, and the operational amplifier 72 of the third amplifying unit 71. Output to the other input terminal 93.
[0039]
For this reason, the gain by the third amplifying unit 71 can be changed in 256 stages according to the input 8-bit digital signal, and this output is sent to the operational amplifier 72 and the connector 81 of the third amplifying unit 71. It is possible to output to the outside of the air micrometer via the assigned analog output unit 94. Thereby, the change to the measurement range according to the digital signal can be realized.
[0040]
Therefore, when changing to a range other than the preset measurement range, or when changing to a larger number of measurement ranges, change the switch provided in the device body, change the jumper pin connection, change the internal circuit wiring, Compared to the conventional case that requires replacement of the resistance, the operation of removing the main body cover or removing the built-in substrate is not required. Thereby, the range can be changed by the user, and convenience is improved.
[0041]
On the other hand, in the zero adjustment unit 203, a zero adjustment signal having a voltage corresponding to the digital signal input from the outside is output from the output terminal 233 of the operational amplifier 211 via the resistor 213 to the digital IC 73 of the third amplification unit 71. The input terminal 202 is input. As a result, a voltage obtained by adding the voltage of the zero adjustment signal to the output voltage from the second amplifying unit 51 is added to the input terminal 202 of the digital IC 73 in the third amplifying unit 71.
[0042]
Therefore, the voltage that changes according to the back pressure and is amplified by the above-described gain can be moved up and down relatively by the zero adjustment signal that is changed according to the digital signal.
[0043]
As described above, this allows fine zero adjustment by the user without removing the main body cover or removing the built-in substrate, further improving convenience.
[0044]
【The invention's effect】
As described above, in the A / E converter according to claim 1 of the present invention, the voltage that changes according to the back pressure from the measuring element is amplified with a gain according to the digital signal input from the outside. The output signal corresponding to this voltage can be output to the outside. Thereby, the change to the measurement range according to the digital signal can be performed.
[0045]
Therefore, when changing to a range other than the preset measurement range, or when changing to a larger number of measurement ranges, change the switch provided in the device body, change the jumper pin connection, change the internal circuit wiring, Compared to the conventional case that requires replacement of the resistance, the operation of removing the main body cover or removing the built-in substrate is not required. Thereby, the range can be changed by the user, and convenience is improved.
[0046]
In the A / E converter according to claim 2, the voltage that changes according to the back pressure and is amplified by the gain described above is relatively moved by a zero adjustment signal that is changed according to the digital signal. Can be output.
[0047]
As described above, this allows fine zero adjustment by the user without removing the main body cover or removing the built-in substrate, further improving convenience.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a first embodiment of the present invention.
FIG. 2 is a circuit diagram of a main part showing a second embodiment of the present invention.
FIG. 3 is a block diagram showing the same embodiment;
4A is an equivalent circuit of the first D / A converter of FIG. 3, and FIG. 4B is an equivalent circuit of the second D / A converter of FIG.
FIG. 5 is a block diagram showing a conventional air micrometer.
FIG. 6 is an explanatory diagram showing the operation of the conventional changeover switch.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 A / E converter 11 Differential pressure sensor 42 1st amplification part 51 2nd amplification part 71 3rd amplification part 82 Digital input part 94 Analog output part 203 Zero adjustment part

Claims (2)

In an A / E converter that converts back pressure from a probe into an electrical signal,
Voltage output means for outputting a voltage that changes according to the magnitude of the back pressure from the probe;
A digital signal input means for inputting a digital signal from the outside;
Amplifying means for amplifying the voltage from the voltage output means with a gain corresponding to the digital signal from the digital signal input means;
External output means for outputting an output signal corresponding to the voltage amplified by the amplification means to the outside;
An A / E conversion device comprising: Comprising zero adjustment signal output means for outputting a zero adjustment signal consisting of a voltage corresponding to a digital signal input from the outside;
2. The A / E according to claim 1, wherein the external output means adds the zero adjustment signal from the zero adjustment signal output means to the voltage amplified by the amplification means to form the output signal. Conversion device.

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